Knowledge base
Freeze-dried or dissolved: why peptides come as a powder
Research peptides are almost always supplied as a freeze-dried powder, not as a ready-made solution. There is a reason: in dry form a peptide stays stable far longer. This article explains what freeze-drying (lyophilisation) is, why the powder sometimes looks different than you expect and when to dissolve a vial.
What is lyophilisation?
In lyophilisation, or freeze-drying, a solution of the peptide is first frozen. The pressure is then lowered sharply, so the ice turns directly into water vapour without melting first (sublimation). What remains is a dry, porous cake or a loose powder in the vial.
With almost no water left, the chemical reactions that break down a peptide, such as hydrolysis and oxidation, slow down. That is why a freeze-dried peptide is far more stable than a solution.
Why is a solution less stable?
- In water the peptide chain can slowly split (hydrolysis).
- Some amino acids, such as methionine and cysteine, oxidise faster in solution.
- Asparagine and glutamine can change structure in solution (deamidation).
- A pierced vial can become microbially contaminated; that is why bac water contains a preservative.
What does the powder look like?
A freeze-dried peptide is usually a white cake or a white powder. Sometimes it lies as a thin layer on the bottom or against the wall, and with a few mg the vial can look almost empty. A cake that has collapsed or turned sticky can point to moisture or heat.
Not every powder is white: GHK-Cu is blue because of the copper.
When do you dissolve a vial?
Only dissolve a vial when you need it, and choose a strength you will use up while the solution keeps (see Choosing a strength). Dissolving itself is explained step by step in Dissolving peptides; work out the concentration with the peptide calculator.
Storage: powder and solution
- Powder: cool, dry and dark; briefly in the fridge (2–8 °C), longer in the freezer (−20 °C or colder).
- Solution: in the fridge (2–8 °C), never in the freezer.
- More detail in Storing peptides.
Frequently asked questions
- What does lyophilised mean?
- The same as freeze-dried: the water has been removed from the material by freeze-drying (lyophilisation).
- Why is there so little powder in the vial?
- A few mg is a small amount; as a thin layer the vial can easily look almost empty. How much peptide was measured is on the certificate, under the measured content.
- Why are peptides not sold as a solution?
- In solution a peptide breaks down faster. As a powder it stays stable far longer, also during shipping.
- Is a dissolved peptide still the same substance?
- Yes. It is the same substance, now in water. Dissolved in a known volume, it gives a solution of known concentration.
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For laboratory research only. BrabantLabs products are intended for laboratory research and not for human or animal use. This article describes what has been published in the scientific literature and is not a health claim or advice on use.